Are there any questions that are out of bounds because of Tzeni'uth or just an "ick" factor that might elicit inappropriate responses (of the anti-religious sort)?
Well, the FAQ says:
Please respect that in the Jewish tradition certain questions, especially certain questions relating to sexuality, are discussed only in private. Such questions will be closed or deleted at the discretion of the moderators or community.
based on discussion over at this meta post.
However, the lines are rather vague. I'd say if you really feel uncomfortable with a question to flag it and explain why you feel that way and perhaps the mods will delete it.